The present invention relates to a device for picking up objects without making physical contact with the object. More particularly, the present invention relates to a device for picking up objects by utilizing a flow of a gas, such as air, without the need for providing lateral restraints to prevent the object from lateral movement.
There are many applications in which it is desired to pick up an object without contacting the object with any mechanical means, such as the fingers or mechanical devices such as prongs or tweezers or the like. For example, semiconductor wafers are particularly susceptible to damage from mechanical contact during handling. One such contactless lifter device is described in U.S. Pat. No. 3,438,668 to Olsson et al. The Olsson et al. patent described a contactless lifter which utilizes the Bernoulli principle to provide a pick-up device that utilizes a flow of a gas, such as air, to provide the pick up force and to provide a cushion between the object being picked up and the pick up device.
The pick up device of the Olsson et al. patent utilizes a plurality of projections around the periphery of the device to provide lateral restraint of the object being picked up. It is undesirable to use such lateral restraints for delicate objects, such as semiconductor wafers, since the object being picked up tends to float on the surface of the pick up device and to impinge upon the lateral restraint projection. Such impingement on the lateral restraint projections can mar on fracture the edge of an undesirable number of the delicate objects upon contact of the object with the restraining projection. The undesirable features of the Olsson et al. patent and other prior art methods for picking up objects are overcome by the present invention which utilizes the same flow of gas used to produce the pick up force to provide a lateral restraining force.